Rub pork loin with garlic and thyme and season well with salt and pepper. Drizzle with olive oil. Marinate in a plastic bag for at least 2 hours to overnight.
Brown all sides and roast on a rack in a roasting pan in a preheated 350 degree oven. Cook until center of loin reaches 160 degrees, about 1 hour and 20 minutes. Allow to rest for 10 minutes before carving.